Rubber compositions comprising dibromopolybutadiene and a solid polyamide

ABSTRACT

Described is a rubber composition comprising dibromopolybutadiene and the reaction product between aliphatic polyamines and polycarboxylic acids or anhydrides. The compositions are preferably used as low temperature adhesives or sealers.

BACKGROUND OF THE INVENTION

In the fabrication of adhesives and coating compositions, it ispreferred that these compositions have the ability to cure at lowtemperatures thereby resulting in an energy savings. Additionally, thesecompositions should have the ability of a long pot life and thereforehave substantial stability, preferably being one-component; that is, allof the reactant components are included in one place. Liquid rubbercompositions containing dibromopolybutadiene are known. However,extended pot life and low curing temperatures have not been achievedpreviously for said compositions.

SUMMARY OF THE INVENTION

The invention is concerned with rubber compositions comprising:

A. dibromopolybutadiene;

B. a polyamide which is the reaction product of a polyamine and apolycarboxylic acid or anhydride. Preferably, the rubber compositionalso contains additional amounts of an epoxy resin. The polyamide actsas a curing catalyst.

DESCRIPTION OF PREFERRED EMBODIMENTS

Dibromopolybutadiene is a known composition and is generally availablein the trade usually as a liquid.

The reaction product of the polyamine and the polycarboxylic acid oranhydride are also known products. The preparation of these products isdescribed in U.S. Pat. No. 3,639,657 which is hereby incorporated byreference.

Preferably, the reaction product is prepared by a condensation reactionto produce a polyamide wherein the polyamine is comprised of saturatedaliphatic amines. The polyamines are generally of the structure(R₁)(R₂)N--R₃ --N(R₄)(R₅) wherein R₁, R₂, R₄, and R₅ are independentlyselected from the groups consisting of hydrogen and alkyl of 1 to 6carbon atoms, and R₃ is selected from the group consisting of (i)saturated alkylene groups from 2 to 8 carbon atoms; (ii) a cyclicstructure including the amino groups such as piperazine and the like;(iii) compounds of the structure --(CH₂)_(a) --N(R₆)--(CH₂)_(b) -- or##STR1## WHEREIN A, B, C, D, AND E INDEPENDENTLY ARE INTERGERS RANGINGFROM 1 TO 4, AND R₆ may be hydrogen or alkyl of 1 to 6 carbon atoms.

Suitable amines are ethylene diamine, diethylene triamine, triethylenetetraamine, 1,6 -diamino hexane, 1,3 -diamino propane, imino-bis (propylamine), methyl imino-bis (propyl amine) and the like.

The polycarboxylic acid or anhydride may be saturated aliphatic orcycloaliphatic or aromatic and may contain from 3 to 12 carbon atomssuch as citric acid, phthalic anhydride, hexahydrophthalic anhydride,tetrahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride andthe saturated aliphatic polycarboxylic acids and anhydrides such asoxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic,sebacic and the like.

Most preferably, the polyamide that is employed is one that is a lowmolecular weight product preferably less than 1,000, even morepreferably less than 500. Additionally, the reaction product ispreferably water soluble.

The use of the rubber composition of the present invention is preferablyemployed with an epoxy resin. The epoxy resin is any one of the normallycommercially available epoxy resins such as epoxy resins of thebisphenol-A type, dimeric acid type, polyalkylene ether type, novolaktype, the polyhydric alcohol type as the reaction product of bisphenoland epihalohydrin and the like.

It is to be appreciated that various inert materials are added toimprove the properties of the composition such as reinforcing agents,pigments, plasticizers and the like.

It should also be appreciated that other promoting catalysts or agentscan be added to increase the curing speed of the composition.

During the utilization of the composition of the present invention, theadhesive may be applied to one or two substrates which are to be adheredtogether. The substrates may then be affixed to each other and theadhesive subsequently cured. The substrates are normally metallicsubstrates or one is trying to secure one substrate to a metallicsubstrate such as that as normally occurs in the transportation industryas in automobiles, trucks and the like. The substrates may be metal aszinc, iron, or aluminum, wood, glass, plastic, as synthetic resins andthe like.

The amides that are used as curing catalysts for the present compositionhave the particular advantage that the total composition (one package)is stable at room temperature, and therefore can be shipped and handledwith little or no difficulty. It is only when the temperatureapproximates 65° C. and above that the catalyst melts and is dissolvedinto the butadiene component thereby causing the catalytic reaction tooccur and the vulcanization or curing of the rubber composition.

The components of the invention can be described as follows:

    ______________________________________                                                       Broad Range                                                                              Preferred Composition                                 Materials    (Parts/Wt.)                                                                              (Parts/Wt.)                                         ______________________________________                                        Dibromopolybutadiene                                                                         100        100                                                 (DBPB)                                                                        Polyamide catalyst                                                                           3-200      34                                                  Epoxy resin    0-300      24                                                  ______________________________________                                    

Another area where the composition of the present invention may beemployed is in the area of a sealant, such as a low cost sealant thatmay be applied to seal various crevices, such as the underbody of anautomobile. Because the polyamide catalyst is a solid at ambienttemperature and pressure, there is virtually no curing of the DBPB. Theproduct is very stable at ambient.

If the DBPB polyamide composition were blended with appropriatediluents, than a low cost auto undercoating could be produced. Thecoating can be applied at any desired thickness although 10-20 mils ispreferred.

The diluents that may be employed range in an amount from about 1 toabout 5 parts of diluent to one part of DBPB.

Suitable diluents are those that are relatively non-reactive and stablewith respect to DBPB and the polyamide such as asphalt such as onehaving a softening point of 85°-110° F., oil such as naphthenic,aromatic or paraffinic oil, hydrocarbon resins as terpene derivatives,and the like.

It is to be appreciated that the compositions of the present invention,regardless of end use, may have added thereto various plasticizers,thermal and light degredation stabilizers, pigments, reinforcingmaterials, solvents and the like.

Suitable plasticizers that may be used are those that do not dissolvethe polyamide catalyst until its melting point has been reached such asdiisodecyl phthalate, dioctly phthalate, butyl benzyl phthalate, and thelike.

Suitable stabilizers may be lead phthalate, organic phosphates, zinc andits oxides, and various other vinyl stabilizers as long as they do notinterfere with the adhesion of the composition to the substrate.

Suitable pigments and fillers may be calcium carbonate, titaniumdioxide, barium-calcium type, calcium magnesium carbonate, and the like.

Any solvent may be used as long as it does not dissolve the polyamidecatalyst for the catalyst will cause premature curing. Therefore,solvents such as ketones and alcohols should not be used.

Having described the invention in general terms, listed below arefurther embodiments of the invention wherein all temperatures are indegrees Fahrenheit and all parts are parts by weight.

EXAMPLE 1.

An adhesive formulation was prepared as follows:

Rtv-1500 (trademark of Polysar Corporation for dibromopolybutadiene) 60parts by weight,

Epoxy resin (reaction product of bisphenol and epichlorhydrin) 20.5parts;

Polyamide catalyst (Reaction product of phthalic anhydride anddiethylene triamine; the product has a melting point of 102°-103° C. andan equivalent weight of 93) 14.5 parts by weight.

Bentone (Trademark of National Lead for a gelling agent) 12.4 parts byweight.

Calcium magnesium carbonate 100 parts by weight.

The mixture is blended together and is stable at room temperature forextended periods of time. The mixture is applied to a steel substrateand heated to about 130° C. thereby melting the polyamide resulting in acured, hard adhering coating.

Texanol isobutyrate solvent 50 parts by weight may be used to dilute theabove composition in order to assist in applying the adhesive.

EXAMPLE 2.

A sealing composition was formulated as follows:

    ______________________________________                                        asphalt            200 parts by weight                                        Naphthenic oil     200 parts by weight                                        DBPB               100 parts by weight                                        HY 940*             17 parts                                                  ______________________________________                                         *Trademark of Ciba-Geigy for a mixture of an epoxy resin (10 parts) of th     bisphenol epichlorohydrin type and polyamide catalyst (7 parts) of Exampl     1.                                                                       

The above composition was stable at room temperature for an extendedperiod of time. When the composition was applied to the underbody of avehicle, the vehicle heated to 130° C., the polyamide catalystdissolved, resulting in a hard, adherent sealing composition.

The consistency of the coating composition can be varied from hard tosoft and rubbery by adding more diluent and less epoxy material to thesealing composition.

It is to be appreciated that variations on the invention can be madewithout departing from the scope of the appended claims such as usingthe sealing or undercoating composition wherever vinyl sealingcompositions may be used for better chip resistance can be achieved bythe oil extended sealing compositions described herein.

What is claimed is:
 1. A one package rubber composition consistingessentially of a mixture of dibromopolybutadiene and an effectivecatalytic amount of the reaction product of a saturated aliphaticpolyamine and a saturated aliphatic carboxylic acid or anhydride or anaromatic or cycloaliphatic acid or anhydride wherein the reactionproduct is an amide that is solid at ambient temperature and pressure.2. The composition of claim 1 further comprising an epoxy resin in anamount ranging from about 10 to about 300 parts by weight per 100 partsby weight of dibromopolybutadiene.
 3. The composition of claim 1 whereinthe polyamide product has a molecular weight of less than 1,000.
 4. Thecomposition of claim 1 wherein the polyamide has a molecular weight ofless than
 500. 5. The composition of claim 1 wherein the polyamide is asolid and is present in an amount ranging from about 3 parts by weightto 200 parts by weight per 100 parts by weight of dibromopolybutadiene.6. The composition of claim 1 further comprising a diluent present in anamount ranging from about 1 to about 5 parts by weight of diluent per 1part by weight of dibromopolybutadiene.
 7. A one package adhesive orsealing composition consisting essentially of a mixture ofdibromopolybutadiene and an effective catalytic amount of the reactionproduct of a saturated aliphatic polyamine and a saturated aliphaticcarboxylic acid or anhydride or an aromatic or cycloaliphatic acid oranhydride wherein the reaction product is an amide that is solid atambient temperature and pressure.
 8. The composition of claim 7 whereinthe polyamide is a solid and is present in an amount ranging from about3 parts of weight to 200 parts by weight per 100 parts by weight ofdibromopolybutadiene.
 9. The composition of claim 7 wherein a diluent ispresent in an amount ranging from about 1 to about 5 parts by weight ofdiluent per 1 part by weight of dibromopolybutadiene.
 10. A method ofadhering two substrates to each other comprising applying thecomposition of claim 1 to a first substrate at room temperature;affixingthe second substrate to the first substrate; and curing said compositionby heating said substrates to a temperature of at least 65° C.
 11. Theprocess of claim 10 wherein the polyamide has a molecular weight lessthan 1,000.
 12. The process of claim 10 wherein the polyamide has amolecular weight less than
 500. 13. The process of claim 10 wherein thecomposition further comprises an epoxy resin in amount ranging fromabout 10 to about 300 parts by weight (PBW) per 100 PBW ofdibromopolybutadiene.
 14. The cured product on the substrates of claim10.